LED driver design maximises efficiency of high voltage leds

Power Integrations has published a reference design (DER-297) describing a high efficiency, ultra compact driver for a B10 style led light bulb.

Based on the company's LinkSwitch-PL non isolated, single stage led driver IC, the power supply is specifically tailored for use with high voltage leds.

DER-297 is designed to provide the high voltage output required by the leds, optimising overall system efficiency by reducing power lost due to current flow in the driver inductor and output diode.

The power supply design has a BOM of 20 components, while the level of integration in the LinkSwitch-PL device combines PFC and constant current functions into a single buck boost stage requiring one tiny inductor. According to Power Integrations, the design reaches 87% efficiency at 115Vac for a 4.3W led driver (86% for 2.9W output) while achieving a power factor greater than 0.9, meeting EN61000-3-2 Class C limits, and creating less than 20% total harmonic distortion.

Andrew Smith, product marketing manager for led applications at Power Integrations, said: "The tiny B10 and similarly compact form factors are very challenging for led lamps. The LinkSwitch-PL device used in DER-297 permits the driver to be both small and highly efficient, which allows us to pack the design into a B10 base without using potting compound or compromising performance. The simple BOM also means that the converter has a very low cost, making DER-297 ideal for this increasingly price competitive market."